The present invention relates to a carpet having pile threads forming a pile layer, a support layer which consists of fiber or strip material of polyolefins or polyesters, and a back coating, the pile threads being possibly bound by the back coating to the support layer, and consisting of a plastic of comparatively high temperature resistance, in particular polyamide 6 or 6.6, the back coating being bonded as lamination to the upper material.
The method of manufacture and the construction of such carpets are known. One object of the invention is so further to develop a carpet of this type that an extremely firm bonding of the layers to each other is obtained and that the possibility of recycling the carpet is also not limited by this after suitable treatment.
This object is achieved in, that the back coating is formed by means of a lamination adhesive which contains unmelted polyamide fibers. The other layers of the carpet can preferably also consist of plastic, for instance polypropylene and/or polyethylene. Over the back coating of the support material, the carpet can furthermore, in particular, have a back layer which is also referred as second back. In accordance with the invention, the lamination between the back layer and the support layer (also referred to as top material) is made particularly stable, namely directly by the lamination adhesive which also forms the back coating. Since the back layer and the support layer are formed of plastic, namely of polyolefins, in particular fibrous materials of polyolefins, namely preferably polypropylene or polyethylene, not only is an improvement of the carpet itself obtained but its recycling is also made possible. The polyamide fibers or other fiber components of the lamination adhesive do not prevent the reuse of the carpet but even favor it. The fiber portions of the lamination adhesive are, in particular, so selected that they are proportionate to the pile threads of the carpet. If, for instance, 30% fibers are contained in the carpet (referred to the mass), it is preferable that the lamination adhesive from which the back coating is formed also has 30% fibers (identical fibers). It is furthermore preferred that the lamination adhesive contain thermoplastic portions having a base of polyolefins. In addition to this, also portions of styrene/acrylate and/or styrene/butadiene, polyvinyl acetate, etc. Furthermore, antistatic additives in the form of carbon or conductive metallized fibers as well as chemical additives, for instance potassium formate (which is, for instance, conductive), etc. Due to the fact that a particularly firm bond is obtained between the support layer and the back layer, even a bonded carpet can be torn off again without parts remaining attached to the floor. The lamination adhesive also contains only (substantially similar) plastic portions so that, also in this way, recycling of the carpet is not limited despite improved adherence conditions. With regard to the thermoplastic polyolefin portions contained in the lamination adhesive, it is furthermore preferred that the lamination adhesive contain thermoplastic portions having a base of polyethylene. Furthermore, the lamination adhesive can also contain thermoplastic portions having a base of polypropylene. All being raw materials which are also contained in the carpet itself. In addition to this, the lamination adhesive can contain portions of styrene/acrylate and/or styrene/butadiene and/or polyvinyl acetate. It is also preferred that the lamination adhesive contain conductive components. For example, carbon fibers or metallized conductive fibers (the latter again preferably having a base of polyamide). In this way, the lamination adhesive can be made conductive, which is essential in the case of carpets for special uses, particularly computer rooms. Due to the fact that the lamination adhesive used contains fibrous components have a base of polyamide or the like, a conspicuous dull appearance of this layer is obtained when the layer formed by the lamination adhesive has hardened, which is of importance, for instance, if the back layer consists of a comparatively coarse fabric through which the lamination adhesive is apparent. Furthermore, an advantageous, textile-like character of a layer formed in this manner is obtained. This is of importance, for instance, if only the layer of lamination adhesive is applied to the previously produced top material and the second back is not used.
A carpet formed in this manner consists, as a whole, preferably of a pile material of polyamide 6 and/or polyamide 6.6 or the like. This pile material is needled into a support material of polypropylene forming the support layer, either a polypropylene nonwoven or a polypropylene ribbons. The anchoring of the pile material in the top material is furthermore preferably effected by means of a precoat having a base of copolymers of, for instance styrene/acrylate, styrene/butadiene, polyvinyl acetate, and the like. Furthermore, a lamination adhesive is present between the top material and the so-called second back. This lamination adhesive contains, for instance, polyamide portions (substantially in the form of unmelted polyamide fibers) of about 15 to 35%. Furthermore, a proportion of polyolefins of about 60-80%. Further portions, which may be desired for the adjustment of the conductivity of the lamination layer or are to be added to the component styrene/acrylate or the like, are present in an amount of about 3 to 6%. Preferred compositions of the lamination adhesive are, for instance 15 to 35% polyamide, 3 to 6% styrene/acrylate and 60 to 80% polyolefins (polypropylene, polyethylene, or the like). The second back can be a knitted or woven fabric, a nonwoven fabric or the like.
Another object of the invention is an adhesive in powdered or granulated form, particularly a lamination adhesive, for instance for the production of a carpet in one of the embodiments described above. In this connection, the adhesive furthermore has unmelted fiber components of polyamide or the like, for instance polyester, which are attached to each other by thermoplastic portions having a base of polyolefins, such as, for instance, polypropylene and/or polyethylene. These last-mentioned thermoplastic portions result in the desired adhesive action. For this purpose, the action of heat is necessary, it melting the polyolefin components but not the fiber portions having a base, in particular, of polyamide. For example, polyamide has a melting point of about 220.degree. C. while the polyolefins used melt already at about 120.degree. to 130.degree. C. Furthermore, the adhesive may contain conductive substances, for instance conductive fibers or corresponding additions of chemical products. It is also preferred for the adhesive to contain portions of styrene/acrylate and/or styrene/butadiene, polyvinyl acetate, and the like.
A further object of the invention is a method of producing a lamination adhesive in powdered or granulated form, particularly an adhesive such as described above, preferably for use in a (further) production of carpets. In this connection, fibers having a base of polyamide or the like, for instance the pile material of a carpet, are subjected, together with thermoplastic plastics of, for instance, polyolefins, particularly polypropylene, polyethylene, etc., to the action of heat in such a manner that the fiber components, without themselves melting, are bonded to each other by molten thermoplastic material. For thee carrying out thereof, the agglomerates obtained are ground to granulate or powder form. Such a method can preferably be carried out in the manner that complete components of a carpet which consists essentially of pile material having a base of polyamide, in particular polyamide 6 and/or polyamide 6.6 or the like, and furthermore of components having a base of polyolefins, namely polypropylene and/or polyethylene, etc., are torn into small pieces and then agglomerated in a so-called "plastcompactor". A plastcompactor grinds these components, whereby a certain amount of heat is developed, leading to the melting of the low thermoplastic portions but not to the melting of the polyamide portions or the like. From the plastcompactor there is obtained a granulate-like mass which is introduced into a fine grinder. Temperatures which cause the melting of the fibrous polyamide pieces are not reached in the fine grinder. A powder obtained in this manner can be mixed with, for instance, pure polyethylene, for instance in an amount of 30%.